Fast-rate thermoelectric device

ABSTRACT

A fast-rate thermoelectric device control system includes a fast-rate thermoelectric device, a sensor, and a controller. The fast-rate thermoelectric device includes a thermoelectric actuator array disposed on a wafer, and the thermoelectric actuator array includes a thin-film thermoelectric (TFTE) actuator that generates a heating and/or a cooling effect in response to an electrical current. The sensor is configured to measure a temperature associated with the heating or cooling effect and output a feedback signal indicative of the measured temperature. The controller is in communication with the fast-rate thermoelectric device and the sensor, and is configured to control the electrical current based on the feedback signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of prior-filed, co-pending U.S.application Ser. No. 17/038,614, filed Sep. 30, 2020, the content ofwhich is herein incorporated by reference in its entirety.

STATEMENT OF GOVERNMENTAL INTEREST

This invention was made with Government support under contract numberHU0001-15-2-0028 awarded by the Uniformed Services University of theHealth Sciences (USU). The Government has certain rights in theinvention.

BACKGROUND

This disclosure relates generally to thermoelectric devices, and moreparticularly, to fast-rate thermotactile actuators.

Thermoelectric devices utilize a thermoelectric effect to directlyconvert an electric power input into a temperature differential togenerate a heating effect or cooling effect. This thermoelectric effect,referred to as the “Peltier effect,” is achieved by connecting togethertwo different thermoelectric materials, one being a p-type material andthe other being an n-type material, with a metal interconnect to form anelectrical junction. Applying a voltage across the junction induces acurrent flow, thereby cooling at this junction (producing a coolingeffect) while rejecting heat at the opposite end of the junction(producing a heating effect).

However, attempts to improve conventional thermoelectric devices forapplications requiring reduced device packaging and enhanced figures ofmerit at practical temperatures, as well as high heating/cooling powerdensity and speed, have been unsuccessful in the past. Thus, what isneeded is an improved thermoelectric device having these, and other,improvements.

BRIEF DESCRIPTION

According to a non-limiting example embodiment, a fast-ratethermoelectric device control system includes a fast-rate thermoelectricdevice that includes a thermoelectric actuator array disposed on awafer, the thermoelectric actuator array including a thin-filmthermoelectric (TFTE) actuator configured to generate one or both of aheating effect and a cooling effect in response to an electricalcurrent. The fast-rate thermoelectric device control system furtherincludes at least one sensor configured to measure a temperatureassociated with one or both of the heating effect and the cooling effectand to output a feedback signal indicative of the measured temperature,and a controller in communication with the fast-rate thermoelectricdevice and the at least one sensor. The controller is configured tocontrol the electrical current based at least in part on the feedbacksignal.

According to another non-limiting example embodiment, fast-ratethermoelectric device includes a thermoelectric actuator array disposedon a wafer and including a plurality of TFTE actuators, each configuredto generate one or both of a heating effect and a cooling effect inresponse to an electrical current, a first power contact node connectedto a first TFTE actuator included in the thermoelectric actuator array,and configured to receive a first voltage polarity, and a second powercontact node connected to a second TFTE actuator included in thethermoelectric actuator array and configured to receive a second voltagepolarity.

According to yet another non-limiting example embodiment, a TFTEactuator includes a backplate and a p-n couple disposed on thebackplate. The p-n couple includes a superlattice thermoelectricmaterial and a thermally conductive layer connected to the superlatticethermoelectric material, and is configured to vary in temperature inresponse to an electrical current flowing through the p-n couple.

According to still another non-limiting example embodiment, a method ofproviding thermotactile stimulation includes disposing a fast-ratethermoelectric device against a surface, providing an electrical currentto the fast-rate thermoelectric device, selectively generating one orboth of a heating effect and a cooling effect via the fast-ratethermoelectric device in response to a direction of the electricalcurrent, and providing the heating effect or the cooling effect to thesurface.

Additional features and advantages are realized through the techniquesof the present disclosure. Other embodiments and aspects of thedisclosure are described in detail herein. For a better understanding ofthe disclosure with the advantages and the features, refer to thedescription and to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter is particularly pointed out and distinctly claimed inthe claims at the conclusion of the specification. The forgoing andother features and advantages of the non-limiting example embodimentsdescribed herein are apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram illustrating a fast-rate thermoelectricactuator according to a non-limiting embodiment;

FIG. 2 is a block diagram illustrating a fast-rate thermoelectric deviceincluding a plurality of thermoelectric actuators according to anon-limiting embodiment;

FIG. 3 is a block diagram illustrating a fast-rate thermoelectric deviceoperating in a heating mode according to a non-limiting embodiment;

FIG. 4 is a block diagram illustrating a fast-rate thermoelectric deviceoperating in a cooling mode according to a non-limiting embodiment;

FIG. 5A is a graph of temperature versus time depicting an example of acooling response of a fast-rate thermoelectric device according to anon-limiting embodiment compared to a cooling response of a conventionalthermoelectric cooling device;

FIG. 5B is a graph of temperature versus time depicting an example of acooling response of a fast-rate thermoelectric device according toanother non-limiting embodiment compared to a cooling response of aconventional thermoelectric cooling device;

FIG. 6 is a block diagram illustrating a fast-rate thermoelectric devicecontrol system according to a non-limiting embodiment;

FIG. 7 is a block diagram illustrating a fast-rate thermoelectric devicecontrol system configured to exchange data wirelessly according to anon-limiting embodiment;

FIG. 8 illustrates a plurality of fast-rate thermoelectric devicesdisposed against a surface according to a non-limiting embodiment;

FIG. 9 depicts a method of providing thermotactile stimulation accordingto a non-limiting embodiment;

FIG. 10 depicts a classifier system according to a non-limitingembodiment;

FIG. 11 depicts a learning phase that can be implemented by a classifiersystem according to a non-limiting embodiment; and

FIG. 12 depicts a computer system according to a non-limitingembodiment.

DETAILED DESCRIPTION

The performance of a thermoelectric device is typically based on theenergy conversion efficiency (for both heating and cooling) of thedevice's thermoelectric material. This efficiency is determined by thematerial's “figure of merit” (ZT), which is defined by the followingequation:

${{ZT} = \frac{\alpha^{2}T}{\rho K_{t}}},$

where α, T, ρ, and K_(t) are the Seebeck coefficient, absolutetemperature, electrical resistivity and total thermal conductivity,respectively.

Conventional thermoelectric devices employ bulk materials (i.e.,non-superlattice materials) such as bulk bismuth telluride (Bi₂Te₃)alloys, for example, as the thermoelectric material used to form theelectrical junction. However, these conventional bulk materials exhibithigh lattice thermal conductivity, and hence lower figure of merit ZT,and also offer low cooling power density and lower speed of cooling. Asa result, conventional thermoelectric devices, and in particularthermoelectric cooling and/or heating actuators, have proven to beunsuccessful in achieving a significantly enhanced figure of merit (ZT)at practical temperatures, e.g., ZT>2 at temperature ranges from about200 degrees kelvin (K) [about −73 degrees Celsius (° C.)] to about 400 K(about 127° C.). As a result, attempts to employ conventionalthermoelectric devices in certain applications, such as those requiringreduced device packaging that provides an enhanced figure of merit (ZT)at practical temperatures, as well as high cooling power density andhigher cooling speed, have been unsuccessful in the past.

Various non-limiting example embodiments described herein include afast-rate thermoelectric device including thin-film thermoelectricmaterials capable of significantly enhancing the figure of merit (ZT) ofthe device, high cooling power density, and faster cooling speedscompared to bulk thermoelectric cooling devices. The cooling speed ofthe fast-rate thermoelectric device described herein is inverselyproportional to the thickness of the thin-film thermoelectric material(e.g., a squared value of the thin-film thermoelectric materialthickness). In this manner, the increased cooling speed is essentiallythe same as a human biological cooling response, thereby leading tothermotactile feasibility in various applications. For example, thefast-rate thermoelectric device can be utilized to apply heat pulsesand/or cold pulses to regenerate nerve damages, check human responses,and identify nerve damage.

In one or more non-limiting embodiments, the thin-film thermoelectricmaterial includes a p-type superlattice material and other embodimentsof the superlattice or an n-type superlattice material and otherembodiments of the superlattice. In some embodiments, the p-typesuperlattice material includes bismuth/antimony telluride(Bi₂Te₃/Sb₂Te₃) which facilitates improved carrier mobility (e.g.,control and transport of phonons and electrons) therein, therebyproviding a fast-rate thermoelectric actuator having enhanced figure ofmerit (ZT)>2 (i.e., ZT=˜2) near 300K (about 27° C.), or in some exampleseven higher, e.g., ZT=˜2.4.

In other example (non-limiting) embodiments, the p-type superlatticematerial or the n-type superlattice material is a controlledhierarchical engineered superlattice structure (CHESS), referred toherein as a “CHESS structure.” These CHESS structures can be formedhaving superlattice periods of varying thicknesses and associated layersof varying thicknesses, in a controllable and reliable format, to obtaina structure that scatters a range of phonons. In this manner, afast-rate thermoelectric actuator employing a CHESS structure as thethin-film thermoelectric material can further enhance the figure ofmerit (ZT) to be significantly greater than 2, e.g., about 2.8 (i.e.,ZT˜2.8) near 300K (about 27° C.).

In one or more non-limiting embodiments, a fast-rate thermoelectricdevice includes an array of individual fast-rate thermoelectricactuators. Each thermoelectric device includes a p-n couple and severalsuch p-n couples are connected in series to act in unison to providethermal actuation. The individual fast-rate thermoelectric actuators aredisposed, e.g., are formed, on a wafer and are connected electrically inseries with one another, but thermally parallel. A voltage potential canbe applied across the array so as to induce an electrical flow throughthe individual fast-rate thermoelectric actuators. The current flowinduces a rapid thermal response (e.g., a rapid heating effect or rapidcooling effect) that is produced from the surface of the fast-ratethermoelectric device. In one or more non-limiting embodiments, thefast-rate thermoelectric device is configured for placement directlyagainst a surface including, but not limited to, skin (e.g., humanskin). Accordingly, the rapid-thermal response is quickly applied to thesurface in time scales that are consistent with human biologicalresponse needs, in response to current flowing through individualfast-rate thermoelectric actuators. In this manner, the fast-ratethermoelectric device can rapidly convey changes in thermal sensation toindividuals through contact with the skin for many applicationsincluding, but not limited to, biomedical thermotactile applications. Itis worth noting that this above array can also be a series-parallelconfiguration, thereby able to utilize a variety of current and voltageinputs. For example, a 12-couple array can be a 3-by-4 (3×4), or 2×6, or4×3, etc., where, in the 3×4 array, 3 couples are electrically in serieswith each other, and 4 such 3-couple strings are electrically inparallel with each other.

Turning now to FIG. 1 , a thermoelectric actuator, which in one or moreexample embodiments is a thin-film thermoelectric (TFTE) actuator 100,is shown. The TFTE actuator 100 includes a backplate 102, a p-leg 104(e.g., a positive voltage terminal), an n-leg 106 (e.g., a negativevoltage terminal), and a p-n couple 108. The backplate 102 can have athickness ranging, for example, from about 0.5 millimeters (mm) to about50 micrometers (μm) and can be formed from various thermally conductivematerials. In an example embodiment, the backplate 102 may include, orbe, a wafer, described in greater detail below with respect to FIG. 2 ,though alternative embodiments are neither limited nor restrictedthereto. In one or more non-limiting, example embodiments, the thermallyconductive material of the backplate 102 includes aluminum nitride(AlN). A thermally conductive interface 103 may also be included, whichenhances thermal conductivity between the backplate 102 and the p-leg104 and/or the n-leg 106. It will be appreciated, however, that thethermally conductive interface 103 can be omitted without departing fromthe spirit or scope of the example embodiments described herein.

In the example embodiment shown in FIG. 1 , the p-leg 104 and the n-leg106 are disposed on, e.g., are formed on, the thermally conductiveinterface 103. The p-leg 104 and the n-leg 106 are each formed from anelectrically conductive material. In one or more non-limitingembodiments, each of the p-leg 104 and the n-leg 106 are formed asseparated arrangements of thermally conductive layers. As shown in FIG.1 , for example, an opposing pair of lower conductive layers 110, eachcorresponding to a respective one of the p-leg 104 and the n-leg 106, isdisposed, e.g., is formed, on the surface of the thermally conductiveinterface 103. An electrically conductive enhancing layer 112 isdisposed, e.g., is formed, on the upper surface of each lower conductivelayer 110. The electrically conductive enhancing layer 112 has a lowerelectrical resistance than the lower conductive layer 110, to improvethe electrical conductivity between the p-leg 104 and the n-leg 106 andthe p-n couple 108. In one or more non-limiting embodiments, the lowerconductive layer 110 is formed, for example, from copper (Cu), while theelectrically conductive enhancing layer 112 is formed from gold (Au). Itwill be appreciated, however, that the usage of copper and gold to formthe p-leg 104 and n-leg 106 is only one example, and that combinationsof other electrically conductive materials can be employed to form thep-leg 104 and the n-leg 106 without departing from the spirit or scopeof the example embodiments described herein.

The p-n couple 108 includes one or more p-type TFTE elements 114, one ormore n-type TFTE elements 116, a thermally conductive layer 118, and acontact header 120. The p-type TFTE elements 114 include a first endthat is disposed (e.g., formed) on a bottom surface (as viewed in FIG. 1) of the thermally conductive layer 118 and an opposing second endconfigured to contact the p-leg 104. An ohmic contact can be establishedbetween the p-type TFTE elements 114 and the p-leg 104 using, forexample, an electrically conductive element 122 (e.g., a contact pad orsolder bump) including a low-resistance ohmic material such as, forexample, indium (In). In at least one non-limiting embodiment, thep-type TFTE element 114 includes a p-type Bi₂Te/Sb₂Te₃ superlatticethermoelectric material, which facilitates improved carrier mobility(e.g., control and transport of phonons and electrons) therein. Althoughthe p-n couple 108 is illustrated in FIG. 1 as having two p-type TFTEelements 114, it will be appreciated that less (e.g., one) or additional(e.g., more than two) TFTE elements 114 can be employed withoutdeparting from the spirit or scope of the example embodiments describedherein. Similarly, the n-type TFTE elements 116 include a first end thatis disposed (e.g., formed) on a bottom surface of the thermallyconductive layer 118 and an opposing second end configured to contactthe n-leg 106. An ohmic contact (e.g., another electrically conductiveelement 122) can be disposed between the n-type TFTE elements 116 andthe n-leg 106 using, for example, a contact pad or solder bump includinga low-resistance ohmic material such as, for example, indium (In). In atleast one non-limiting embodiment, the n-type TFTE element 116 includesan n-type Bi₂Te₃/Bi₂Se₃/Bi₂Se_(x)Te_(3-x) superlattice thermoelectricmaterial, which facilitates improved carrier mobility (e.g., control andtransport of holes) therein. Although the p-n couple 108 is illustratedas having two n-type TFTE elements 116, it will be appreciated that less(e.g., one) or additional (e.g., more than two) TFTE elements 116 can beemployed without departing from the spirit or scope of the exampleembodiments described herein.

In one or more non-limiting embodiments, the p-type TFTE elements 114and the n-type TFTE elements 116 are each formed of a superlatticethermoelectric material including a CHESS structure, as described inU.S. patent application Ser. No. 15/700,263, “Superlattice Structuresfor Thermoelectric Devices,” filed Sep. 11, 2017, and published as U.S.Pat. Publication No. 2018/0138106, which are hereby incorporated byreference in their entireties. In at least one non-limiting embodiment,the p-type TFTE elements 114 include a p-type superlattice structureincluding Bi₂Te₃/Sb₂Te₃ and the n-type TFTE elements 116 include ann-type superlattice structure including Bi₂Te₃/Bi₂Se₃. As describedherein, a CHESS structure can include superlattice periods of varyingthicknesses and associated layers of varying thicknesses, in acontrollable and reliable format, to obtain a structure that scatters arange of phonons. In this manner, the TFTE actuator 100 can operate as afast-rate thermoelectric actuator 100 having an enhanced figure of merit(ZT) that is greater than about 2.8 (i.e., ZT=˜2.8) near 300K (about 27°C.).

The p-n couple 108 operates according to the Peltier effect to directlyconvert an electric power input into a temperature differential togenerate a heating effect and/or a cooling effect. For instance, the p-ncouple 108 establishes a p-n junction between the p-type TFTE elements114 and the n-type TFTE elements 116. Applying a negative polarityvoltage (V−) to the p-leg 104 and a positive polarity voltage (V+) tothe n-leg 106 generates a voltage potential, which induces a currentflow from n-leg 106, through the p-n couple 108 and to the p-leg 104.The current flow from the n-leg 106 to the p-leg 104 induces cooling atthe thermally conductive layer 118 and produces a cooling effect at thethermally conductive layer 118, while rejecting heat toward the p-leg104 and the n-leg 106. The cooling is transferred to the contact header120 where a thermotactile effect occurs, while the heat is indirectlytransferred to the backplate 102. Accordingly, a surface (e.g., humanskin) in contact with the contact header 120 can realize thethermotactile effect (e.g., the cooling effect).

Similarly, a heating effect is produced in response to causing currentto flow in the opposite direction described above. Specifically, forexample, applying a positive polarity voltage (V+) to the p-leg 104 anda negative polarity voltage (V−) to the n-leg 106 generates a voltagepotential that induces a current flow in the opposite direction, i.e.,from p-leg 104, through the p-n couple 108 and to the n-leg 106. In thisscenario, the current flow from the p-leg 104 to the n-leg 106 inducesheating at the thermally conductive layer 118, while rejecting heat,i.e., cooling, thereby lowering temperatures at/toward the p-leg 104 andthe n-leg 106. The heat from the thermally conductive layer 118 istransferred to the contact header 120 where a heating thermotactileeffect occurs, while the cooling is indirectly transferred to thebackplate 102. Accordingly, a surface (e.g., human skin) in contact withthe contact header 120 can realize the heating thermotactile effect.

Turning now to FIG. 2 , a fast-rate thermoelectric device 200 isillustrated according to a non-limiting embodiment. The fast-ratethermoelectric device 200 includes a thermoelectric actuator array 202disposed, e.g., formed, on a wafer 204. The thermoelectric actuatorarray 202 includes a plurality of the TFTE actuators 100 (FIG. 1 )configured to generate one or both of a heating effect and a coolingeffect in response to an electrical current (I). The TFTE actuators 100are described in greater detail above with reference to FIG. 1 .

In at least one non-limiting embodiment, the thermoelectric actuatorarray 202 includes a plurality of the thin-film thermoelectric (TFTE)actuators 100 disposed/formed on an electrically conductive trace 205such that the thin-film thermoelectric (TFTE) actuators 100 areconnected in electrical series with one another. The electricallyconductive trace 205 can be formed of various metals including, but notlimited to, copper (Cu), silver (Ag), gold (Au), tin (Sn), aluminum(Al), or combinations thereof. Although the thermoelectric actuatorarray 202 is illustrated FIG. 2 as being arranged in a 3-by-4 (3×4)matrix or array, i.e., 3 “rows” and 4 “columns” of TFTE actuators 100(for a total of 12 TFTE actuators 100), additional or alternativeexample embodiments of the thermoelectric actuator array 202 are notlimited thereto and may have smaller or larger array arrangements ordesigns (e.g., arrays of 2×2, 10×20, 30×10, etc.).

The thermoelectric actuator array 202 according to an example embodimentincludes a first power contact node 206 a and a second power contactnode 206 b. The first power contact node 206 a is in signalcommunication with a first TFTE actuator 100 a included in thethermoelectric actuator array 202. A second TFTE actuator 100 b isconnected to the first TFTE actuator 100 a via the electricallyconductive trace 205, and so on along the electrical path created by theelectrically conductive trace 205, to a last (n-th) TFTE actuator 100 n(not all TFTE actuators 100 are labeled in FIG. 2 ; note also that, inthe case where there are only two TFTE actuators, i.e. where n=2, thesecond TFTE actuator 100 b is the last (n-th) TFTE actuator 100 n). Thesecond power contact node 206 b is connected to the n-th (last) TFTEactuator 100 n included in the thermoelectric actuator array 202. In anexample embodiment, the first power contact node 206 a is configured toreceive a first voltage polarity V+ (i.e., a voltage having a positivepolarity V+), while the second power contact node 206 b is configured toreceive a second voltage polarity V− (i.e., a voltage having a negativepolarity V−) or, alternatively, is connected to ground. It will beappreciated that the polarities of the voltages, i.e., the first andsecond voltage polarities, applied to the first and second power contactnodes 206 a and 206 b, respectively, can be reversed to reverse thedirection of a current (I), as described in greater detail below.Because the TFTE actuators 100 are arranged in series, the alternatingorientations (e.g., p-n, p-n, p-n, p-n, etc.) of the p-n couplingbeginning at the second power contact node 206 b and ending at the firstpower contact node 206 a are maintained throughout the length of theelectrically conductive trace 205, as shown in FIG. 2 , denoted by theletter “P” or “N,” as appropriate, at each end of a given TFTE actuator100. It will also be appreciated, however, that, in additional exampleembodiments, the TFTE actuators 100 can be arranged such that thealternating orientations (e.g., p-n, p-n, p-n, p-n, etc.) of the p-ncouplings begin at the first power contact node 206 a and ending at thesecond power contact node 206 b. In such an arrangement, the letters “N”and “P” for each of the TFTE actuators 100 would be swapped in FIG. 2 .

The fast-rate thermoelectric device 200 is capable of selectivelyoperating in a cooling mode or a heating mode based on a direction ofcurrent (I) flowing through the thermoelectric actuator array 202.Referring now to FIG. 3 , for example, the fast-rate thermoelectricdevice 200 is illustrated operating in a cooling mode according to anon-limiting embodiment. The first power contact node 206 a is shownconnected to a positive voltage source 208 a, and thus applies apositive polarity voltage (V+) to the n-type TFTE element (N) of thefirst TFTE actuator 100 a. The second power contact node 206 b is shownconnected to a negative voltage source 208 b, and thus applies anegative polarity voltage (V−) to the p-type TFTE element (P) of thelast TFTE actuator 100 n. Accordingly, the positive and negative voltagepolarities V+ and V− establish a voltage potential across thethermoelectric actuator array 202, which induces an electrical current(I) through the individual TFTE actuators 100 from the first powercontact node 206 a to the second power contact node 206 b. As describedin greater detail above, the current (I) flow varies the surfacetemperature of each thin-film thermoelectric (TFTE) actuator 100included in the thermoelectric actuator array 202 such that thecombination of surface temperatures produces a cooling effect. In anexample embodiment, a common contact header (not shown, refer to FIG. 1, described above) can be applied to the upper surface of the TFTEactuators 100. The cooling generated by the TFTE actuators 100 istransferred to the contact header where a thermotactile effect occurs.Accordingly, a surface (e.g., human skin) in contact with the contactheader can realize the thermotactile effect (e.g., cooling effect).

Turning now to FIG. 4 , the fast-rate thermoelectric device 200according to an example embodiment is illustrated operating in a heatingmode. As shown in FIG. 4 , the direction of the flow of the electricalcurrent (I) is opposite that shown in FIG. 3 . Specifically, in theheating mode, the second power contact node 206 b is connected to apositive voltage source 208 a, and thus applies a positive polarityvoltage (V+) to the p-type TFTE element (P) of the last TFTE actuator100 n, while the first power contact node 206 a is connected to anegative voltage source 208 b, and thus applies a negative polarityvoltage (V−) to the n-type TFTE element (N) of the first TFTE actuator100 a. Accordingly, the negative and positive voltage polarities V+ andV+, respectively, establish a voltage potential across thethermoelectric actuator array 202, which induces an electrical current(I) through the individual TFTE actuators 100 from the second powercontact node 206 b to the first power contact node 206 a. As describedabove, the current (I) flow varies the surface temperature of eachthin-film thermoelectric (TFTE) actuator 100 included in thethermoelectric actuator array 202 such that the combination of surfacetemperatures produces a heating effect. In an example embodiment, acommon contact header (not shown, refer to FIG. 1 , described above) canbe applied to the upper surface of the TFTE actuators 100. The heatinggenerated by the TFTE actuators 100 is transferred to the contact headerwhere a thermotactile effect occurs. Accordingly, a surface (e.g., humanskin) in contact with the contact header can realize the thermotactileeffect (e.g., heating effect). The heating mode is effected in responseto the electrical current (I) flowing in the opposite direction fromthat used to effect the cooling mode (FIG. 3 ). In one or morenon-limiting embodiments, the direction of the current (I) can beselectively controlled by a controller (not shown in FIGS. 3 and 4 ),which controls a power supply (not shown in FIGS. 3 and 4 ) thatcontrols and/or includes the positive and negative voltage sources 208 aand 208 b to respectively provide the first and second voltagepolarities V+ and V− to the fast-rate thermoelectric device 200. Acontroller according to an example embodiment is discussed in greaterdetail below with reference to FIG. 6 .

The fast-rate thermoelectric device 200 represented in the exampleembodiments described herein offers a substantial and wide range ofbenefits compared to conventional (bulk) thermoelectric heating andcooling devices. For example, in terms of the cooling effect generatedby the cooling mode (FIG. 4 ), the fast-rate thermoelectric device 200achieves significantly improved high cooling power density and fastercooling speeds compared to bulk thermoelectric cooling devices. Thishigh cooling power density can be applied not only to electronicapplications (e.g., exploited to cool hot-spots in microelectronicchips), but also to biological applications (e.g., human thermotactileand thermal perception). These substantially improved devicecharacteristics provide dramatically increased perception inthermotactile applications and human thermal perceptions at a reducedenergy budget (i.e., an improved energy efficiency with reduced energyexpenditure) in comparison to conventional thermoelectric coolingdevices. The fast-rate thermoelectric device 200 according to one ormore example embodiments provides similar, substantial benefits andimprovements over conventional thermoelectric devices.

Turning to FIGS. 5A and 5B, graphs 500 a and 500 b, respectively,illustrate an example of a cooling effect 502 provided by the fast-ratethermoelectric device 200 compared to the cooling effect 504 provided bya conventional thermoelectric cooling device. More specifically, graph500 a illustrates differences, in temperature over time, between thecooling response 502 of the fast-rate thermoelectric device 200 and thecooling response 504 of a conventional thermoelectric cooling device toabout 16° C. (about 289 K), while graph 500 b illustrates differencesbetween the cooling response 502 of the fast-rate thermoelectric device200 and the cooling response 504 of a conventional thermoelectriccooling device to about 11.6° C. (about 285 K). As shown in FIGS. 5A and5B, the fast-rate thermoelectric device 200 achieves a significantlyfaster cooling response 502 time; specifically, the cooling response 502of the fast-rate thermoelectric device 200 according to an exampleembodiment is faster than the cooling response 504 of a conventionalthermoelectric cooling device by a factor of approximately 8, i.e., thefast-rate thermoelectric device 200 is 8 times more effective incomparison to a conventional thermoelectric cooling device. In additionto the substantially improved performance of the fast-ratethermoelectric device 200 (nearly 8 times faster than a conventionalthermoelectric cooling device), as indicated by the time scale of thefast-rate thermoelectric device 200 cooling effect 502, e.g., reaching atarget temperature of about 16° C. (FIG. 5A) or 11.6° C. (FIG. 5B) isachieved in about 3 seconds, which is effectively equivalent to that ofa typical thermal response time perceived by humans, while theconventional thermoelectric cooling device takes about 25 seconds toachieve a similar cooling effect. It will be appreciated, however, thatthe fast-rate thermoelectric device 200 is not limited to theaforementioned cooling response, and it will be appreciated that thefast-rate thermoelectric device 200 is capable of achieving even fastercooling response times such as, for example, about 300 hundredmilliseconds, or even less. Also, it will be noted that, while coolingresponse times have been shown and described with reference to FIGS. 5Aand 5B, that benefits and improvements afforded by the fast-ratethermoelectric device 200 are not necessarily limited to cooling, e.g.,the fast-rate thermoelectric device 200 is configured to provide bothheating and cooling thermotactile responses, as described above withreference to FIGS. 3 and 4 , for example.

The improved cooling response time provided by the fast-ratethermoelectric device 200 also has a profound benefit in terms of theenergy budget necessary to achieve a targeted thermotactile response,i.e., it provides a significant improvement in energy efficiency. Table1 and Table 2 below illustrate differences between the power input andenergy budget for a typical conventional (bulk) thermoelectric coolingdevice and the fast-rate thermoelectric device 200. More specifically,Table 1 shows the power input and energy budget for a typicalconventional thermoelectric cooling device and for the fast-ratethermoelectric device 200 for achieving a cold-side temperature of 16°C. (FIG. 5A). Table 2 illustrates the power input and energy budget fora typical conventional thermoelectric cooling device and the fast-ratethermoelectric device 200 for achieving a cold-side temperature of 11.6°C. (FIG. 5B).

TABLE 1 Power Response Energy Device I (Amp) V (Volts) (Watt) time (Sec)(Joules) Conventional 0.4 0.23 0.092 25 2.3 TE Device Fast-Rate 1.1 0.30.33 3 0.99 TE Device 200

TABLE 2 Power Response Energy Device I (Amp) V (Volts) (Watt) time (Sec)(Joules) Conventional 0.7 0.42 0.3 25 7.5 TE Device Fast-Rate 1.7 0470.8 3 2.4 TE Device 200

As can be seen from Tables 1 and 2, the fast-rate thermoelectric device200 has the higher power levels associated with it, which is to beexpected due to its significantly increased cooling power densityrelative to conventional thermoelectric cooling devices. However, due tothe vastly superior cooling time response provided by the fast-ratethermoelectric device 200, the actual energy budget (defined as theintegration of power over the time of current flow) is substantiallylower for the fast-rate thermoelectric device 200, despite havingslightly higher input power. More particularly, the fast-ratethermoelectric device 200 is about 2.4 to 3.0 times more energyefficient for thermotactile functionality compared to conventionalthermoelectric cooling devices, due to the combination of increasedcooling speed (improved matching with human thermal response) andincreased cooling power density.

With reference now to FIG. 6 , a fast-rate thermoelectric device controlsystem 300 according to a non-limiting embodiment. The fast-ratethermoelectric device control system 300 includes a controller 304 andone or more sensors 302 a, 302 b, etc. (for brevity, only two sensors302 shown in FIG. 6 , but additional example embodiments are neitherlimited nor restricted thereto). The controller 304 is in signalcommunication with the fast-rate thermoelectric device 200 and thesensor(s) 302, and is configured to control the electrical current (I)described in greater detail above. In one or more non-limitingembodiments, the controller 304 controls the electrical current (I)based at least in part on a feedback signal 306 corresponding to aparticular sensor. Specifically, for example, a first sensor 302 a canbe a temperature sensor disposed or included in the fast-ratethermoelectric device 200, and be configured to measure a temperatureassociated with one or both of the heating effect and the cooling effectdescribed above and output a first feedback signal 306 a indicative ofthe measured temperature. A second sensor 302 b, for example, may be acurrent sensor disposed or included in the fast-rate thermoelectricdevice 200, and configured to measure the input current level and outputa second feedback signal 306 b indicative of the input current level. Ineither example (or both), the controller 304 can control the fast-ratethermoelectric device 200 to maintain a targeted output temperature,while taking into account surrounding environmental temperatures and/ora temperature of a surface (e.g., human skin) on which the fast-ratethermoelectric device 200 is disposed.

In one or more non-limiting embodiments, the controller 304 includes aprocessor 308, a memory 310, and a power supply 312. The processor 308is configured to execute algorithms and computer-readable programinstructions stored in the memory 310. The power supply 312 generatesvoltages, such as the first voltage polarity V+ (a voltage having apositive polarity V+) and the second voltage polarity V− (a voltagehaving a negative polarity V− or ground), which can be applied to thefast-rate thermoelectric device 200 to induce the electrical current(I), as described in greater detail above and, to that end, may include,incorporate, or instantiate the positive voltage source 208 a and thenegative voltage source 208 b.

The processor 308 is configured to selectively switch the power supply312 on and off, vary the voltage level to control the level of theelectrical current (I) flowing through the fast-rate thermoelectricdevice 200 and/or change the polarity of the voltage (e.g., from V+ toV− and vice versa) to change the direction of the electrical current (I)flowing through the fast-rate thermoelectric device 200. In at least oneembodiment, the processor 308 selects a first voltage polarity thatapplies a first voltage potential across the thermoelectric actuatorarray 202. Accordingly, the electrical current flows through thethermoelectric actuator array 202 in a first direction to invoke thecooling mode of the fast-rate thermoelectric device 200, as described ingreater detail above with reference to FIG. 3 . Further, the processor308 can dynamically select a second voltage polarity (e.g., an oppositepolarity to that of the first voltage polarity) that applies a secondvoltage potential across the thermoelectric actuator array 202 and thusinvokes the heating mode of the fast-rate thermoelectric device 200(discussed above with respect to FIG. 4 ). Selection of the voltagepolarities can be in response to artificial intelligence operations,machine learning algorithms, and/or manual inputs from a user, althoughalternative example embodiments are not limited thereto.

The processor 308 is further configured to control the power supply 312and/or vary the voltage level based on the measured temperatureindicated by the feedback signal 306. In one or more embodiments, theprocessor 308 is configured to determine a target temperature, comparethe measured temperature to the target temperature and control the powersupply 312 and/or vary the voltage level based on the comparison. Thetarget temperature can be selected or input to the processor 308 by auser, for example. The processor 308 can continuously perform thecomparison and actively controls the power supply 312 so as to maintainthe measured temperature at the target temperature.

In one or more non-limiting embodiments, the fast-rate thermoelectricdevice control system 300 is configured to wirelessly exchanging data.As shown in FIG. 7 , for example, the controller 304 is configured towirelessly communicate with one or more mobile terminal devices 400. Inthis manner, the controller 304 and mobile terminal device(s) 400 canexchange one or more data signals 402 therebetween. The mobile terminaldevice 400 can include, but is not limited to, a laptop computer,computer tablet, smartphone, and smart wearable device. The data signals402 indicate various types of information and data including, but notlimited to, external environmental temperatures, weather data, themeasured temperature indicated by the feedback signal, power commandsfor controlling the electrical current, target thermoelectric devicetemperatures, and temperature profiles.

In one or more non-limiting embodiments, the data signal 402 generatedby the mobile terminal device 400 commands the controller 304 to controlthe temperature generated by the fast-rate thermoelectric device 200. Inat least one non-limiting embodiment, the controller 304 is configureddetermine one or more temperature profiles based on various machinelearning algorithms performed either locally or by the mobile terminaldevice 400, which are then exchanged with the controller 304.

Turning now to FIG. 8 , a plurality of fast-rate thermoelectric devices200 a, 200 b, and 200 c are shown disposed against a surface 800. Thesurface 800 can include, but is not limited to, an electronic device, asemiconductor chip, an integrated circuit component, soft tissue, andhuman skin (such as, for example, skin on a human limb). Although thefast-rate thermoelectric devices 200 a, 200 b, and 200 c are showndirectly contacting an exterior portion of the surface 800, it will beappreciated that one or more of the fast-rate thermoelectric devices 200a, 200 b, and 200 c can be disposed beneath the surface 800. Inscenarios where the surface 800 is human skin, for example, one or moreof the fast-rate thermoelectric devices 200 a, 200 b, and 200 c can bedisposed beneath the surface 800, e.g., subcutaneously, allowing thefast-rate thermoelectric device to contact soft tissue.

As described herein, the fast-rate thermoelectric devices 200 a, 200 b,and 200 c are configured to apply a thermotactile stimulation 802 a, 802b, and 802 c, respectively, to the surface 800. The thermalthermotactile stimulations 802 a, 802 b, and 802 c can include, forexample, a cooling effect. In one or more non-limiting embodiments, thethermotactile stimulations 802 a, 802 b, and 802 c (e.g., a coolingeffect and/or a heating effect) can be applied to and/or penetrate intothe surface 800. In example embodiments where the surface includes humanskin or a human limb, the penetrating cooling effect and/or the heatedeffect induces a thermotactile sensation perceived by a human, thoughalternative example embodiments are not limited thereto, as thethermotactile sensation may also be applied to and perceived bynon-humans (other animals), for example. In individuals with limbamputation, for example, one or more fast-rate thermoelectric devices200 a, 200 b, and 200 c can be disposed against or on one or morelocations 804 a, 804 b, 804 c, respectively, on, in, or neat the surface800 of an amputated site of the residual limb. The generated coolingeffect and/or the heating effect can penetrate through the skin and softtissue of the amputated site and reach functioning free nerve endingssubcutaneously. Accordingly, the thermotactile stimulations 802 a, 802b, 802 c (e.g., a cooling effect) achieved by the fast-ratethermoelectric device 200 provides realistic, real-time, and meaningfulthermal information to individuals with limb amputation for creatingcomplex, multimodal sensations in a natural and fully embodiedprosthesis, which simply cannot be achieved using conventionalthermoelectric cooling devices.

In one or more non-limiting embodiments, a controller (e.g., thecontroller 304 shown in FIGS. 6 and 7 ) can synchronize the fast-ratethermoelectric devices 200 a, 200 b, and 200 c for various temporalbehaviors. For example, the fast-rate thermoelectric devices 200 a, 200b, and 200 c can be synchronized to operate in unison, or can operateoffset with respect to one another by a set time. The unison and offsetoperations can be selected by the controller 304, or may be selectedmanually (by an individuals with a limb amputation, for example).

It will be understood that, although three fast-rate thermoelectricdevices 200 a, 200 b, and 200 c are shown in FIG. 8 , along with threecorresponding respective locations 804 a, 804 b, 804 c, and threecorresponding thermotactile stimulations 802 a, 802 b, 802 c,respectively, that alternative example embodiments are neither limitednor restricted thereto, and that any number of fast-rate thermoelectricdevices may be provided and disposed accordingly to allow differentthermotactile stimulations in different locations.

One or more non-limiting example embodiments include providing thethermotactile stimulations described above using the fast-ratethermoelectric device 200 shown and described herein, as will now bedescribed in further detail with reference to FIG. 9 . As shown in FIG.9 , a method 900 for providing thermotactile stimulation includes, in afirst step 910, disposing a fast-rate thermoelectric device against asurface (e.g., human skin). The method 900 further includes providing(e.g., delivering) an electrical current to the fast-rate thermoelectricdevice (step 920), selectively generating one (or both) of a heatingeffect and a cooling effect via the fast-rate thermoelectric device, inresponse to a direction of the electrical current (step 930), andproviding (e.g., delivering) the heating effect and/or the coolingeffect to the surface (step 940). Additional details of the method 900(and associated steps 910, 920, 930, and 940) have been shown anddescribed in greater detail herein and, for purposes of brevity, willnot be repeated here. It will be understood, however, that additional oralternative example embodiments of providing thermotactile stimulationmay include any or all features shown or described herein, and thatadditional example method embodiments include, for example,manufacturing the devices shown and described herein.

The computer control functionality described herein can be implementedusing machine learning and/or natural language processing techniques. Ingeneral, machine learning techniques are run on so-called “neuralnetworks,” which can be implemented as programmable computers configuredto run a set of machine learning algorithms. Neural networks incorporateknowledge from a variety of disciplines, including neurophysiology,cognitive science/psychology, physics (such as statistical mechanics),control theory, computer science, artificial intelligence,statistics/mathematics, pattern recognition, computer vision, parallelprocessing and hardware [e.g., digital/analog/very large scaleintegration (VLSI)/optical/etc.].

The basic function of neural networks and their machine learningalgorithms is to recognize patterns by interpreting unstructured sensordata through a kind of machine perception. Unstructured real-world datain its native form (e.g., images, sound, text, or time series data) isconverted to a numerical form (e.g., a vector having magnitude anddirection) that can be understood and manipulated by a computer. Themachine learning algorithm performs multiple iterations oflearning-based analysis on the real-world data vectors until patterns(or relationships) contained in the real-world data vectors areuncovered and learned. The learned patterns/relationships function aspredictive models that can be used to perform a variety of tasks,including, for example, classification (or labeling) of real-world dataand clustering of real-world data. Classification tasks often depend onthe use of labeled datasets to train the neural network (i.e., themodel) to recognize the correlation between labels and data. This isknown as supervised learning. Examples of classification tasks includedetecting people/faces in images, recognizing facial expressions (e.g.,happy, angry, etc.) in an image, identifying objects in images (e.g.,stop signs, pedestrians, lane markers, etc.), recognizing gestures invideo, detecting voices, detecting voices in audio, identifyingparticular speakers, transcribing speech into text, and the like.Clustering tasks identify similarities between objects, which aregrouped according to those characteristics in common, and whichdifferentiate them from other groups of objects. These groups are knownas “clusters.”

An example of machine learning techniques that can be used to implementaspects of the example embodiments described herein will be describedwith reference to FIGS. 10 and 11 . Specifically, machine learningmodels configured and arranged according to example embodiments will bedescribed with reference to FIG. 10 . A more detailed implementation ofportions of the machine learning models shown in FIG. 10 will bedescribed with reference to FIG. 11 . Detailed descriptions of anexample computing system and network architecture capable ofimplementing one or more example embodiments described herein will beprovided with reference to FIG. 12 .

FIG. 10 depicts a block diagram showing a classifier system 2100 capableof implementing various aspects of the example embodiments describedherein. More specifically, the functionality of the classifier system2100 is used in example embodiments to generate various models andsub-models that can be used to implement computer functionality inexample embodiments described herein. In one example embodiment, theclassifier system 2100 includes data sources 2102, e.g., a plurality ofdata sources 2102 including therein data sources “A,” “B,” and “C” shownin FIG. 10 , in communication through a network 2104 with a classifier2110. According to some non-limiting embodiments, the data sources 2102can bypass the network 2104 and feed directly into the classifier 2110,though this is not shown in FIG. 10 . The data sources 2102 providedata/information inputs that will be evaluated by the classifier 2110 inaccordance with example embodiments. The data sources 2102 also providedata/information inputs that can be used by the classifier 2110 to trainand/or update model(s) 2116 created by the classifier 2110. The datasources 2102 can be implemented as a wide variety of data sources,including but not limited to, sensors configured to gather real timedata, data repositories (including training data repositories), andoutputs from other classifiers. The network 2104 can be any type ofcommunications network, including but not limited to local networks,wide area networks, private networks, the Internet, and the like.

The classifier 2110 can be implemented as algorithms executed by aprogrammable computer such as a processing system 2400 (FIG. 12 ). Asshown in FIG. 10 , the classifier 2110 includes a suite of machinelearning (ML) algorithms 2112, natural language processing (NLP)algorithms 2114, and model(s) 2116 that are relationship (or prediction)algorithms generated (or learned) by the ML algorithms 2112. Thealgorithms 2112, 2114, 2116 of the classifier 2110 are depictedseparately for ease of illustration and explanation. In various exampleembodiments, the functions performed by the algorithms 2112, 2114, 2116of the classifier 2110 can be distributed differently than shown in FIG.10 . For example, where the classifier 2110 is configured to perform anoverall task having sub-tasks, the suite of ML algorithms 2112 can besegmented such that a portion of the ML algorithms 2112 executes eachsub-task, and a portion of the ML algorithms 2112 executes the overalltask. Additionally, in some example embodiments, the NLP algorithms 2114can be integrated within the ML algorithms 2112.

The NLP algorithms 2114 include speech recognition functionality thatallows the classifier 2110 and, more specifically, the ML algorithms2112, to receive natural language data (text and audio) and applyelements of language processing, information retrieval, and machinelearning to derive meaning from the natural language inputs andpotentially take action based on the derived meaning. The NLP algorithms2114 used in accordance with example embodiments can also include speechsynthesis functionality that allows the classifier 2110 to translateresult(s) 2120 outputted from the classifier 2110 into natural language(text and audio) to communicate aspects of the result(s) 2120 as naturallanguage communications.

The NLP and ML algorithms 2114, 2112 receive and evaluate input data(e.g., training data and data-under-analysis) from the data sources2102. The ML algorithms 2112 include functionality to interpret andutilize data from the data sources 2102 based on a format thereof. Forexample, where the data sources 2102 include image data, the MLalgorithms 2112 can include visual recognition software configured tointerpret image data. The ML algorithms 2112 apply machine learningtechniques to received training data (e.g., data received from one ormore of the data sources 2102) in order to, over time,create/train/update one or more models 2116 that model the overall taskand the sub-tasks that the classifier 2110 is designed to complete.

Referring now to FIGS. 10 and 11 collectively, FIG. 11 depicts anexample of a learning phase 2200 performed by the ML algorithms 2112 togenerate the above-described models 2116. In the learning phase 2200,the classifier 2110 extracts features from training data and coverts thefeatures to vector representations that can be recognized and analyzedby the ML algorithms 2112. The features vectors created by theclassifier 2110 are analyzed by the ML algorithm 2112 to “classify” thetraining data against a model, such as a target model (or a particularmodel's task) and uncover relationships between and among the resultingclassified training data. Examples of suitable implementations of the MLalgorithms 2112 include but are not limited to neural networks, supportvector machines (SVMs), logistic regression, decision trees, hiddenMarkov Models (HMMs), etc. The learning or training performed by the MLalgorithms 2112 can be supervised, unsupervised, or a hybrid thatincludes aspects of supervised and unsupervised learning. Supervisedlearning is when training data is already available andclassified/labeled. Unsupervised learning is when training data is notclassified/labeled so must be developed through iterations of theclassifier 2110 and the ML algorithms 2112. Unsupervised learning canutilize additional learning/training methods including, for example,clustering, anomaly detection, neural networks, deep learning, and thelike.

When the models 2116 are sufficiently trained by the ML algorithms 2112,the data sources 2102 that generate “real world” data are accessed, andthe “real world” data is applied to the models 2116 to generate usableversions of the results 2120. In some example embodiments, the results2120 can be fed back to the classifier 2110 and used by the MLalgorithms 2112 as additional training data for updating and/or refiningthe models 2116.

According to various non-limiting embodiments, the ML algorithms 2112and the models 2116 can be configured to apply confidence levels (CLs)to various ones of their results/determinations (including the results2120) in order to improve the overall accuracy of the particularresult/determination. When the ML algorithms 2112 and/or the models 2116make a determination or generate a result for which the value of a CL isbelow a predetermined threshold (TH) (i.e., CL<TH), theresult/determination can be classified as having sufficiently low“confidence” to justify a conclusion that the determination/result isnot valid, and this conclusion can be used to determine when, how,and/or if the determinations/results are handled in downstreamprocessing. In contrast, if CL>TH, the determination/result can beconsidered valid, and this conclusion can be used to determine when,how, and/or if the determinations/results are handled in downstreamprocessing. Many different predetermined TH levels can be provided. Thedeterminations/results with CL>TH can be ranked from the highest CL>THto the lowest CL>TH in order to prioritize when, how, and/or if thedeterminations/results are handled in downstream processing.

Thus, according to various non-limiting embodiments, the classifier 2110can be configured to apply confidence levels (CLs) to the results 2120.When the classifier 2110 determines that a CL in the results 2120 isbelow a predetermined threshold (TH) (i.e., CL<TH), the results 2120 canbe classified as sufficiently low to justify a classification of “noconfidence” in the results 2120. If CL>TH, the results 2120 can beclassified as sufficiently high to justify a determination that theresults 2120 are valid. Many different predetermined TH levels can beprovided such that the results 2120 with CL>TH can be ranked from thehighest CL>TH to the lowest CL>TH.

The functions performed by the classifier 2110, and more specifically bythe ML algorithm 2112, can be organized as a weighted directed graph,wherein the nodes are artificial neurons (e.g. modeled after neurons ofthe human brain), and wherein weighted directed edges connect the nodes.The directed graph of the classifier 2110 can be organized such thatcertain nodes form input layer nodes, certain nodes form hidden layernodes, and certain nodes form output layer nodes. The input layer nodescouple to the hidden layer nodes, which couple to the output layernodes. Each node is connected to every node in the adjacent layer byconnection pathways, which can be depicted as directional arrows thateach has a connection strength. Multiple input layers, multiple hiddenlayers, and multiple output layers can be provided. When multiple hiddenlayers are provided, the classifier 2110 can perform unsuperviseddeep-learning for executing the assigned task(s) of the classifier 2110.

Similar to the functionality of a human brain, each input layer nodereceives inputs with no connection strength adjustments and no nodesummations. Each hidden layer node receives its inputs from all inputlayer nodes according to the connection strengths associated with therelevant connection pathways. A similar connection strengthmultiplication and node summation is performed for the hidden layernodes and the output layer nodes.

The weighted directed graph of the classifier 2110 processes datarecords (e.g., outputs from the data sources 2102) one at a time, and it“learns” by comparing an initially arbitrary classification of therecord with the known actual classification of the record. Using atraining methodology knows as “back-propagation” (i.e., “backwardpropagation of errors”), the errors from the initial classification ofthe first record are fed back into the weighted directed graphs of theclassifier 2110 and used to modify the weighted directed graph'sweighted connections the second time around, and this feedback processcontinues for many iterations. In the training phase of a weighteddirected graph of the classifier 2110, the correct classification foreach record is known, and the output nodes can therefore be assigned“correct” values. For example, a node value of “1” (or 0.9) for the nodecorresponding to the correct class, and a node value of “0” (or 0.1) forthe others. It is thus possible to compare the weighted directed graph'scalculated values for the output nodes to these “correct” values, and tocalculate an error term for each node (i.e., the “delta” rule). Theseerror terms are then used to adjust the weights in the hidden layers sothat in the next iteration the output values will be closer to the“correct” values.

FIG. 12 depicts a high-level block diagram of a computer system 2400,which can be used to implement one or more computer processingoperations in accordance with example embodiments. The computer system2400 includes a communication path 2425, which connects the computersystem 2400 to additional systems (not depicted) and can include one ormore wide area networks (WANs) and/or local area networks (LANs) such asthe Internet, intranet(s), and/or wireless communication network(s). Thecomputer system 2400 and, in one example embodiment, additional systems,are in communication via communication path 2425.

The computer system 2400 includes one or more processors, such as theprocessor 308 described above with respect to FIG. 6 , for example. Theprocessor 308 is connected to a communication infrastructure 2404 (e.g.,a communications bus, cross-over bar, or network). The computer system2400 can include a display interface 2406 that forwards graphics, text,and other data from communication infrastructure 2404, or from a framebuffer (not shown) for display on a display unit 2408. The computersystem 2400 also includes a main memory, such as the memory 310 (FIG. 6), which may be random access memory (RAM), and can also include asecondary memory 2412. The secondary memory 2412 can include, forexample, a hard disk drive 2414 and/or a removable storage drive 2416,which may be, for example, a floppy disk drive, a magnetic tape drive,or an optical disk drive. The removable storage drive 2416 reads fromand/or writes to a removable storage unit 2418, and may be, for example,a floppy disk, a compact disc, a magnetic tape, or an optical disk,flash drive, solid state memory, etc., which is read by and written toby the removable storage drive 2416. As will be appreciated, theremovable storage unit 2418 includes a computer readable medium havingstored therein computer software and/or data.

In an alternative example embodiment, the secondary memory 2412 caninclude or interact with other similar means for allowing computerprograms or other instructions to be loaded into the computer system.Such means can include, for example, a removable storage unit 2420 andan interface 2422. Examples of such means can include a program packageand package interface (such as that found in video game devices), aremovable memory chip [such as an erasable programmable read only memory(EPROM), or a programmable read only memory (PROM)] and associatedsocket, and other removable storage units 2420 and interfaces 2422 incommunication to allow software and data to be transferred from theremovable storage unit 2420 into the computer system 2400.

The computer system 2400 can also include a communications interface2424. The communications interface 2424 further allows software and datato be transferred between the computer system 2400 and external devices.Examples of the communications interface 2424 can include a modem, anetwork interface (such as an Ethernet card), a communications port, ora personal computer (PC) card (e.g., a so-called “PCMCIA” card) andassociated slot, etc. Software and data transferred via communicationsinterface 2424 are in the form of signals which can be, for example,electronic, electromagnetic, optical, or using other signals capable ofbeing received by the communications interface 2424. These signals areprovided to the communications interface 2424 via a channel, e.g., thecommunication path 2425. The communication path 2425 carries signals andcan be implemented using wire or cable, fiber optics, a phone line, acellular phone link, a radio frequency (RF) link, and/or othercommunications channels.

Thus, as shown and described herein, various non-limiting exampleembodiments provide a fast-rate thermoelectric device capable of quicklyapplying a rapid thermal response to a surface almost instantaneously.The thermoelectric device includes an array of individual fast-ratethermoelectric actuators, which are connected to one another. A voltagepotential is applied across the array to induce an electrical flowthrough the individual fast-rate thermoelectric actuators. The currentflow induces the rapid thermal response (e.g., a rapid heating effectand/or a rapid cooling effect) that is produced from the surface of thefast-rate thermoelectric device. The fast-rate thermoelectric devicedescribed herein can be placed directly against a surface including, butnot limited to, human skin. In this manner, the fast-rate thermoelectricdevice can rapidly convey changes in thermal sensation to individualsthrough contact with the skin for many applications including, but notlimited to, biomedical thermotactile applications.

In the present description, the terms “computer program medium,”“computer usable medium,” “computer program product,” and “computerreadable medium” are used to generally refer to media such as memory.Computer programs (also called computer control logic) are stored inmemory. Such computer programs, when run, enable the computer system toperform the features of the example embodiments described herein. Inparticular, the computer programs, when run, enable the controller toperform the features and operations described herein. Accordingly, suchcomputer programs can controllers of the computer system.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor “flash” memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

The following definitions and abbreviations are to be used for theinterpretation of the claims and the specification. As used herein, theterms “comprises,” “comprising,” “includes,” “including,” “has,”“having,” “contains” or “containing,” or any other variation thereof,are intended to cover a non-exclusive inclusion. For example, acomposition, a mixture, a process, a method, an article, or an apparatusthat comprises a list of elements is not necessarily limited to onlythose elements but can include other elements not expressly listed orinherent to such composition, mixture, process, method, article, orapparatus.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the describedexample embodiments. As used herein, the singular forms “a”, “an,” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will be further understood thatthe terms “comprises” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, element components, and/or groups thereof.

Additionally, the term “example” or “exemplary” (and variations thereof)are used herein to mean “serving as an example, instance, orillustration.” Any embodiment or design described herein as an “example”or “exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments or designs. The terms “at leastone,” “one or more,” and variations thereof, can include any integernumber greater than or equal to one, e.g., one, two, three, four, etc.The terms “plurality” and variations thereof can include any integernumber greater than or equal to two, e.g., two, three, four, five, etc.The term “connection” and variations thereof can include both anindirect “connection” and a direct “connection.”

The terms “about,” “substantially,” “approximately,” and variationsthereof, are intended to include the degree of error associated withmeasurement of the particular quantity based upon the equipmentavailable at the time of filing the application.

The phrases “in signal communication, “in communication with,”“communicatively coupled to,” and variations thereof can be usedinterchangeably herein and can refer to any coupling, connection, orinteraction using electrical signals to exchange information or data,using any system, hardware, software, protocol, or format, regardless ofwhether the exchange occurs wirelessly or over a wired connection.

Example embodiments are described herein with reference to flowchartillustrations and/or block diagrams of methods, apparatus (systems), andcomputer program products according to example embodiments. It will beunderstood that each block of the flowchart illustrations and/or blockdiagrams, and combinations of blocks in the flowchart illustrationsand/or block diagrams, can be implemented by computer readable programinstructions.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousexample embodiments. In this regard, each block in the flowchart orblock diagrams may represent a module, segment, or portion ofinstructions, which includes one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The corresponding structures, materials, acts, and equivalents of anymeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the example embodiments has been presented for purposesof illustration and description, but is not intended to be exhaustive orlimited to the present invention in the form disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the presentinvention described and shown herein. The example embodiments werechosen and described in order to best explain the principles of thepresent invention and the practical application thereof, and to enableothers of ordinary skill in the art to understand the present inventionfor various embodiments with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. A method of providing thermotactile stimulation,the method comprising: disposing a fast-rate thermoelectric deviceagainst a surface, the fast-rate thermoelectric device comprising: athermoelectric actuator array disposed on a wafer, the thermoelectricactuator array including a thin-film thermoelectric (TFTE) actuatorconfigured to generate one or both of a heating effect and a coolingeffect in response to an electrical current; at least one sensorconfigured to measure a temperature associated with one or both of theheating effect and the cooling effect and to output a feedback signalindicative of the measured temperature; and a controller incommunication with the fast-rate thermoelectric device and the at leastone sensor, the controller configured to control the electrical currentbased at least in part on the feedback signal, wherein the TFTE actuatorcomprises a p-n couple disposed on the wafer, the p-n couple comprising:a p-type controlled hierarchical engineered superlattice structure(CHESS); an n-type CHESS; and a thermally conductive layer in contactwith the p-type CHESS and the n-type CHESS, and is configured to vary intemperature in response to an electrical current flowing therethrough,wherein the p-type CHESS and the n-type CHESS each include superlatticeperiods of varying thicknesses and associated layers of varyingthicknesses to scatter a range of phonons; providing an electricalcurrent to the fast-rate thermoelectric device; selectively generatingone or both of a heating effect and a cooling effect via the fast-ratethermoelectric device in response to a direction of the electricalcurrent; and providing the heating effect or the cooling effect to thesurface.
 2. The method of claim 1, wherein the fast-rate thermoelectricdevice further comprises a plurality of TFTE actuators forming at leastone thermoelectric actuator array, and the TFTE actuators of theplurality of TFTE actuators are connected in electrical series with eachother.
 3. The method of claim 2, wherein a first thermoelectric actuatorarray is disposed at a first location of the surface and applies theheating effect to the first location, and a second thermoelectricactuator array is disposed at a second location of the surface andapplies the cooling effect to the second location.
 4. The method ofclaim 2, wherein the surface includes one or both of human skin and softtissue.
 5. The method of claim 2, wherein each TFTE actuator of theplurality of TFTE actuators comprises a p-n couple disposed on thewafer.
 6. The method of claim 1, wherein the electrical current varies asurface temperature of each TFTE actuator such that a combination ofsurface temperatures of the TFTE actuators produces one or both of theheating effect and the cooling effect.
 7. The method of claim 1, whereinthe controller is further configured to determine a target temperature,compare the measured temperature to the target temperature, and controlthe electrical current based on the comparison to maintain the measuredtemperature at the target temperature.
 8. The method of claim 1, whereinthe controller is further configured to wirelessly communicate with oneor more mobile terminal devices to exchange at least one data signaltherebetween, and the controller is further configured to control theelectrical current based on the at least one data signal.
 9. The methodof claim 1, wherein the at least one sensor includes a current sensor incommunication with the controller, the current sensor is configured tomeasure a current level of an electrical current inputted into thefast-rate thermoelectric device and to output a current feedback signalindicative of the measured current level, and the controller isconfigured to control the electrical current based at least in part onthe current feedback signal.
 10. The method of claim 1, wherein thefast-rate thermoelectric device is disposed on a prosthesis.
 11. Themethod of claim 10, wherein the prosthesis is disposed on the surface,and the providing the heating effect or the cooling effect to thesurface includes providing thermal information to an individual wearingthe prosthesis.
 12. The method of claim 11, further comprisingexchanging one or more data signals between a mobile terminal device anda controller in wireless communication with the mobile terminal device,wherein the providing the heating effect or the cooling effect comprisescontrolling the temperature generated by the fast-rate thermoelectricdevice based on the one or more data signals.
 13. A method of providingthermotactile stimulation, the method comprising: disposing a fast-ratethermoelectric device against a surface, the fast-rate thermoelectricdevice comprising: a thermoelectric actuator array disposed on a waferand including a plurality of thin-film thermoelectric (TFTE) actuators,each configured to generate one or both of a heating effect and acooling effect in response to an electrical current; a first powercontact node connected to a first TFTE actuator included in thethermoelectric actuator array, and configured to receive a first voltagepolarity; and a second power contact node connected to a second TFTEactuator included in the thermoelectric actuator array and configured toreceive a second voltage polarity, wherein the first and second TFTEactuators each comprise a p-n couple disposed on the wafer, and whereinthe p-n couple comprises a p-type controlled hierarchical engineeredsuperlattice structure (CHESS), and an n-type CHESS, the p-type CHESSand the n-type CHESS each including superlattice periods of varyingthicknesses and associated layers of varying thicknesses to scatter arange of phonons; providing an electrical current to the fast-ratethermoelectric device; selectively generating one or both of a heatingeffect and a cooling effect via the fast-rate thermoelectric device inresponse to a direction of the electrical current; and providing theheating effect or the cooling effect to the surface.
 14. The method ofclaim 13, wherein the TFTE actuators of the plurality of TFTE actuatorsare connected in electrical series with one another.
 15. The method ofclaim 13, wherein the p-n couple further comprises a thermallyconductive layer in contact with the superlattice thermoelectricmaterial and configured to vary in temperature in response to anelectrical current flowing therethrough.
 16. The method of claim 13,wherein the first and the second voltage polarities establish a voltagepotential across the thermoelectric actuator array that induces theelectrical current to flow through the thermoelectric actuator arrayfrom the first power contact node to the second power contact node. 17.The method of claim 13, wherein the electrical current varies a surfacetemperature of each of the TFTE actuators such that a combination of thesurface temperatures of each of the TFTE actuators produces one or bothof the heating effect and the cooling effect.
 18. The method of claim13, wherein the fast-rate thermoelectric device is disposed on aprosthesis.
 19. The method of claim 18, wherein the prosthesis isdisposed on the surface, and the providing the heating effect or thecooling effect to the surface includes providing thermal information toan individual wearing the prosthesis.
 20. The method of claim 19,further comprising exchanging one or more data signals between a mobileterminal device and a controller in wireless communication with themobile terminal device, wherein the providing the heating effect or thecooling effect comprises controlling the temperature generated by thefast-rate thermoelectric device based on the one or more data signals.21. The method of claim 11, wherein the surface is skin.
 22. The methodof claim 19, wherein the surface is skin.